ESTRO 2025 - Abstract Book

S1377

Clinical - Lung

ESTRO 2025

MRI will be conducted every three months in the first year and then every six months. The control group receive PCI (hippocampal-avoidance allowed) at a dose of 25 Gy /10 fractions. The primary goal is to assess whether brain MRI surveillance alone is non-inferior to the combination of PCI and MRI for OS, with a hazard ratio target of 1.25. Secondary outcomes include cognitive failure-free survival, QoL, and toxicity. Results: As of 24/09/2024, 42 out of 54 sites have been activated across 7 countries. A total of 134 patients have been enrolled, with 106 patients randomized (53 per arm). The ITT population has a median follow-up of 5.2 months. The median age is 65 years (range 60–70), and gender distribution is balanced (female: n=56; 53%). Most enrolled patients have an ECOG PS of 0 or 1 (n=99; 93%), have LS (n=74; 70%; and predominantly stage III: n=53/91 with available data; 58%). A significant proportion of patients were enrolled in France (n=52; 49.1%), and did not receive immunotherapy as part of their first-line treatment (n=83; 78%).In terms of protocol compliance, among the 53 patients allocated to the control arm (PCI + MRI), 5 did not receive PCI (progression: 1; refusal: 4). Neurocognitive (baseline>85%, >69% at 3 months) and QoL (baseline>80%, >70% at 3 months) assessments. Conclusion: The PRIMALung trial aims to define the role of PCI in managing SCLC in the context of brain MRI surveillance and the growing use of immunotherapy, a trend expected to increase following the ADRIATIC trial results.

Keywords: Trial in progress, small cell lung cancer, PCI

References: 1.

Levy A, Berghmans T, Koller M, et al. PRIMALung (EORTC-1901): PRophylactic cerebral Irradiation (PCI) or active brain MAgnetic resonance imaging (MRI) surveillance in small-cell Lung cancer (SCLC) patients. Lung Cancer. 2024 Oct 24;198:107993.

2926

Digital Poster Initial clinical experience of 1.5T MR-Linac guided adaptive SBRT for lung metastases with target intrafraction tracking and gating MICHELE RIGO, CHIARA DE-COLLE, ANDREA GAETANO ALLEGRA, EDOARDO PASTORELLO, NICCOLO' GIAJ-LEVRA, LUCA NICOSIA, FRANCESCO RICCHETTI, NICOLA BIANCHI, RICCARDO BORGESE, DAVIDE GURRERA, ANTONIO DE SIMONE, STEFANIA NACCARATO, GIANLUISA SICIGNANO, RUGGERO RUGGIERI, FILIPPO ALONGI Advanced Radiation Oncology Deapartment, IRCCS Sacro Cuore Don Calabria, Negrar di Valpolicella, Italy Purpose/Objective: The introduction of Comprehensive Motion Management (CMM) on 1.5T MR-Linac allows for target intrafraction tracking and gating, increasing the sparing of normal tissue without placement of fiducials, ensuring the delivery of highly focused radiation to the tumor while further limiting the dose to adjacent OARs. This feature gives also the opportunity to escalate the dose of radiotherapy. Clinical trials have shown that lung SBRT is burdened by a not negligible risk of grade>=3 toxicity. The continuous tracking might reduce the volume of normal lung and chest wall irradiated, decreasing toxicity without additional radiation exposure. The target gating eliminates the need to define an internal target volume (ITV), which is used to ensure tumor coverage during the breathing cycle, but increases the volume of normal lung irradiated. Material/Methods: In September 2023 CMM was installed at our Institution and used for all lung SBRT on the MR-linac. Patients included had the following characteristics: 1)age >18; 2)radiological diagnosis of lung metastases. Exclusion criteria were contraindications to MR.